This disclosure relates to a capacitor based sensor to detect angles or angular positions.
An angle or an angular position is one of the basic physical parameters needed in many scientific or engineering fields. An angle or an angular position may be determined or measured by many different instruments or methods. Some methods are direct measurements, such as using a compass to measure an angle. Other methods are less direct, such as using a string tied around a wheel. The amount of angle rotated by the wheel can be determined from the linear length of the released or retrieved string and the known radius of the wheel.
Some electrical or electromagnetic methods or sensors may use electrical or electromagnetic properties to determine an angular position or change. These sensors may be more easily integrated with other electronics or microprocessors to make the angle measurements and their applications automatic with less human intervention.
A capacitor based sensor or method is a popular type of sensor or method and is used in many applications. For example, U.S. Pat. No. 6,118,283 and U.S. Pat. No. 6,774,642, other references cited within these patents disclose many prior art sensors used for angular position measurement. The basic idea is that the sensor has several fixed metal plates and several rotating metal plates and that there are dielectric materials separating the fixed plates from the rotating plates. When the rotating plates are rotated to different angular positions, the capacitances between the fixed plates and the rotating plates will change; the angular positions and the capacitances are related. Thus, from knowing the capacitance, the angular position may be determined. In addition, the capacitance may be measured by many known methods.
Due to their design and their intended working environments, various types of capacitor based sensors may have many limitations. Many sensors may not work in extreme temperature or high pressure environments; many may not have desirable accuracy or consistency; many are complicated or have complicated electromagnetic requirements; and many are expensive.
It is desirable to have a sensor or a method that can make angle measurement cheaper, more accurate and simpler, or other desirable properties.